GB2200997A

GB2200997A - Analyser

Info

Publication number: GB2200997A
Application number: GB08702338A
Authority: GB
Inventors: Nigel Buchanan
Original assignee: Liquid Levers Ltd
Current assignee: Liquid Levers Ltd
Priority date: 1987-02-03
Filing date: 1987-02-03
Publication date: 1988-08-17
Also published as: GB8702338D0

Abstract

A fluid analyser, especially for testing the quality of brake fluid in motor vehicles comprises an elongate cylindrical support (5) supporting a pair of electrodes (E1, E2) at one end thereof which are dipped into the brake fluid (F) the container (3) and a circuit in casing (4) for applying a voltage to the electrodes and measuring electrical properties of the fluid. Departures from the norm are indicated by LED's in indicator 1. <IMAGE>

Description

"Analyser" Descrietion The present invention relates to an analyser for testing the quality of fluids and especially but not exclusively to an analyser for testing the quality of automotive brake fluids.

In the passage of time the brake fluid of a motor vehicle deteriorates in quality. In particular there can be an ingress of moisture to the brake fluid as a consequence of the chemical composition of the brake fluid, and the resultant reduction in brake fluid quality causes a deterioration in the braking performance of the motor vehicle.

It is an object of the present invention to provide an analyser which can conveniently test the quality of the brake fluid so that remedial action can be taken if the quality is at an unsatisfactory level.

According to the present invention there is provided an analyser for fluids comprising electrical circuit means including an indicator device, said electrical circuit means being connectable to an electrical power source, and means for placing fluid to be tested in an electrically activated condition, said electrical circuit means further including electrode probe means adapted for placement in said fluid to be tested for testing electrical variations of said fluid from a norm, the arrangement being such that said electrical variations of the fluid are indicated on said indicator device. It has been found that increasing contamination of a fluid eg. brake fluid, alters electrical properties of the fluid and the above analyser by virtue of sensing variation in these electrical properties serves to indicate the degree of contamination of the fluid.

Preferably the fluid is placed in an electrically activated condition by creating a capacitive field in the fluid.

Preferably the indicator device comprises a set of light emitting diodes (L.E.D.'s).

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, wherein: Fig. 1 shows a schematic circuit arrangement of a brake fluid analyser according to the present invention; Fig. 2 shows an isometric view of the analyser in an operative position; Fig. 3 shows graphs of fluid boiling points against water content for various types of brake fluid; and Figs. 4A-B show detail circuit diagrams of a circuit suitable for the circuit arrangement of Fig. 1.

In the passage of time, the brake fluid of a motor vehicle absorbs moisture (water) due to the chemical composition of the fluid. This water absorption causes the boiling point of the brake fluid to be continuously lowered; the graphs of Fig. 4 showing the lowering boiling point for increasing water content for various types of brake fluid, and this water contamination adversely affects braking performance. The analyser 1 shown in the drawings serves to measure the degree of contamination of the brake fluid (ie. brake fluid quality) by sensing the changing electrical property of the fluid which will vary by virtue of the contamination.

The analyser 1 essentially comprises an electrical testing circuit 2 (schematically illustrated in Fig. 1) including selected circuit parameters shown at A and B and an indicator means I which in this example comprises a set of light emitting diodes (L.E.D.'s). The circuit 1 which is connectable to an electrical power source P preferably in the form of a dry battery of suitable voltage further includes electrode probes El, E2 adapted for insertion into brake fluid F contained in fluid reservoir 3.

To test the brake fluid.the circuit 2 firstly functions to move the fluid F from the passive state to the electrically active state by sending a capacitve field into the brake fluid F, and the measurement then taken between the two electrodes El, E2 senses the contamination level of the brake fluid, this measurement being transposed to the scale of the indicator device I, specifically causing appropriate illumination of the L.E.D.'s.

Referring to Fig. 2 the analyser 1 is of a convenient hand held type comprising a casing 4 to house the circuit 2 with the L.E.D.'s of the illuminating device I- mounted on the casing 4 as shown, and the electrodes El, E2 project from an elongate cylindrical portion 5 which facilitates insertion of the electrodes in the fluid F as shown. An on-off switch 6 is provided.

and the power source P in the form of a dry battery (eg. 9 volt) is readily insertable and removable from the casing 4 for replacement.

The circuit 1 will require considerable sensitivity and amplification characteristics to satisfactorily sense and indicate variations in the brake fluid F, and Figs. 4A-B show a suitable circuit in detail. The circuit of Figs. 4A-B includes operational amplifiers OA and semi-conductor devices and is of a compact nature for location in the casing 4; the circuit components are mounted on a circuit boardina conventional manner for ease of installation and removal. In Figs. 4A-B the battery is connected across B1 and B2, and the electrodes El, E2 will be noted. Also shown are the L.E.D.'s 1-4 of the indicator device I.

Whilst the analyser 1 is described for analysing brake fluid it will be understood that the analyser, possibly with some adaption, could be used for analysing other fluids, for example water contamination of diesel fuel.

Claims

1. An analyser for fluids comprising electrical circuit means including an indicator device, said electrical circuit means being connectable to an electrical power source, and means for placing fluid to be tested in an electrically activated condition, said electrical circuit means further including electrode probe means adapted for placement in said fluid to be tested for testing electrical variations of said fluid from a norm, the arrangement being such that said electrical variations of the fluid are indicated on said indicator device.

2. An analyser as claimed in claim 1, wherein the fluid is placed in an electrically activated condition by creating a capacitive field in the fluid.

3. An analyser as claimed in claim 1 or claim 2, wherein the indicator device comprises a set of light emitting diodes (L.E.D.'s).

4. An analyser as claimed in any one of the preceding claims, wherein the electrical circuit means are housed in a casing which is capable of being held by a hand.

5. An analyser as claimed in claim 4, wherein the electrode probe means project axially from said casing.

6. An analyser as claimed in any one of the preceding claims, wherein the electrode probe means include a pair of juxtaposed probe members.

7. An analyser for fluids substantially as hereinbefore with reference to and as illustrated in any one of Figs. 1 and 2 or these figures as modified by Figs.

4A and 4B, of the accompanying drawings.